Structural Engineering & Statics
where the load goes
Concept

Redundancy — where it appears

How many more restraints or members a structure has than equilibrium needs, which is what makes its forces depend on stiffness.

Named by 2 essays across 2 fields — each of them below, with the objects they name alongside it.

m 4 + r 3 − 2j 8 = -1a mechanismm 5 + r 3 − 2j 8 = 0statically determinatem 6 + r 3 − 2j 8 = +1one member too manystatics can answer only the middle case

Counting the unknowns, and finding out whether statics can answer

Two equations per joint, one unknown per member, one per restraint. Subtract, and the sign of the answer says whether the structure is a mechanism, solvable, or beyond what equilibrium alone can settle.

equilibrium · determinacy intactmember 2 removedworst demand 2.03×

The structure that survives losing a member

Every check in this collection asks what a structure carries. None of them asks what is left when part of it is gone — and two frames with the same members, the same weight and the same factor of safety can answer that question completely differently.

structures · robustness

Named alongside it

The objects these essays reach for when they reach for this one.

DeterminacyMechanismAlternative load pathCompatibilityDuctilityIndeterminacyProgressive collapseRobustnessStiffnessZero force member

All concepts